Upload 3.py

3.py

@@ -0,0 +1,110 @@
+class Empty(Exception):
+    pass
+
+class ArrayQueue:
+    DEFAULT_CAPACITY = 10
+
+    def __init__(self):
+        self._data = [None] * ArrayQueue.DEFAULT_CAPACITY
+        self._size = 0
+        self._front = 0
+
+    def __len__(self):
+        return self._size
+
+    def is_empty(self):
+        return self._size == 0
+
+    def first(self):
+        if self.is_empty():
+            raise Empty("Queue is Empty!")
+        return self._data[self._front]
+
+    def dequeue(self):
+        if self.is_empty():
+            raise Empty("Queue is Empty!")
+        answer = self._data[self._front]
+        self._data[self._front] = None
+        self._front = (self._front + 1) % len(self._data)
+        self._size -= 1
+        return answer
+
+    def enqueue(self, e):
+        if self._size == len(self._data):
+            self._resize(2 * len(self._data))
+        avail = (self._front + self._size) % len(self._data)
+        self._data[avail] = e
+        self._size += 1
+        print("Element", e, "is enqueued successfully")
+
+    def _resize(self, cap):
+        old = self._data
+        self._data = [None] * cap
+        walk = self._front
+        for k in range(self._size):
+            self._data[k] = old[walk]
+            walk = (walk + 1) % len(old)
+        self._front = 0
+
+
+def main():
+    q = ArrayQueue()
+    while True:
+        print("\n\tQUEUE OPERATIONS")
+        print("1-Enqueue")
+        print("2-Dequeue")
+        print("3-First Element")
+        print("4-Length of Queue")
+        print("5-Is Empty")
+        print("6-Display Queue")
+        print("7-Exit")
+
+        try:
+            ch = int(input("Enter your choice: "))
+
+            if ch == 1:
+                e = int(input("Enter an element: "))
+                q.enqueue(e)
+
+            elif ch == 2:
+                print("The front element:", q.dequeue(), "is dequeued successfully")
+
+            elif ch == 3:
+                print("First element in the queue is", q.first())
+
+            elif ch == 4:
+                print("Queue length =", len(q))
+
+            elif ch == 5:
+                if q.is_empty():
+                    print("Queue is empty!")
+                else:
+                    print("Queue is not empty!")
+
+            elif ch == 6:
+                if q.is_empty():
+                    print("Queue is empty!")
+                else:
+                    print("Queue elements (front to rear):")
+                    index = q._front
+                    print("|", end=" ")
+                    for _ in range(len(q)):
+                        print(q._data[index], "|", end=" ")
+                        index = (index + 1) % len(q._data)
+                    print()
+
+            elif ch == 7:
+                print("Program exited")
+                break
+
+            else:
+                print("Invalid choice")
+
+        except Empty as e:
+            print(e)
+        except ValueError:
+            print("Please enter a valid number")
+
+
+if __name__ == "__main__":
+    main()